Khalid Hossen, Mahmud Hasan Shihab, Md Robiul Islam
Solar-powered unmanned aerial vehicles (UAVs) are emerging as long-endurance platforms for sensing, communications, and environmental monitoring with low operational emissions. Their performance depends on a tightly coupled energy ecosystem spanning photovoltaic harvesting, hybrid energy storage, power electronics, thermal regulation, aerodynamics, and autonomous flight control. From an energy-systems perspective, solar UAVs act as mobile testbeds for advanced photovoltaics, high–specific-energy batteries, and hybrid power-management strategies that are directly relevant to next-generation grids and storage technologies. This review provides a system-level synthesis of the technologies that define modern solar-powered UAVs, covering crystalline silicon, CIGS, perovskite, and multi-junction PV modules; lithium-based, solid-state, and Li–S storage; maximum power point tracking (MPPT) and power-management architectures; high-aspect-ratio aerodynamic structures; and propulsion and navigation subsystems. Key limitations—including weather-dependent irradiance, thermal and UV-induced material degradation, battery aging at high altitude, and regulatory constraints—are critically assessed to identify barriers to reliable multi-day and multi-week operation. Emerging trends such as flexible perovskite films, structural energy storage, solar–fuel-cell hybrid architectures, adaptive thermal management, and edge-AI autonomy are discussed as enablers of energy-positive, persistent flight. By consolidating fragmented insights from energy, materials, and aerospace literature, this review establishes an integrated framework to guide the design of next-generation solar UAV energy systems.